Mental health organizations can play a key role in enhancing client access to care by working together. However, inter-organizational processes are seldom examined and little is known about how mental health agencies develop and sustain partnerships. Knowledge gaps limit our understanding of how, when, and why mental health systems change and impact service delivery. This dissertation study examines partnership development among mental health organizations and is a first step of a research agenda focused on the evolutionary dynamics of mental health service delivery systems. The emphasis on the complex dynamics of relationships between organizations directly responds to the National Institutes of Health, Office of Behavioral and Social Science Research's (OBSSR's) call for systems thinking approaches in their most recent prospectus. In addition, this study responds to Strategy 4.1 in the National Institute of Mental Health's (NIMH's) strategic plan related to enhancing the public health impact of NlMH-funded work by understanding how organizations and systems affect access and quality care. The specific aims are to examine (1) the distribution of administrative partnerships among a network of mental health organizations, (2) the interaction of organizational characteristics on three partnership conditions (3) the relationship of these conditions on organizational interactions and (4) dynamics of how interactions influence trust, partnership conditions (specifically benefits and conflict) and subsequent interactions between mental health organizations. This project is a mixed methods cross-sectional study of dyads of 40 mental health organizations currently participating in an existing NSF- funded study. Implementation of Evidence Based Practice and Organizational Performance (SES 0724577). Network data on dyadic relationships, archival data from IRS 990 forms, and semi-structured interviews with the five most central organizations will be collected and used to examine how and why mental health organizations partner, and a preliminary system dynamics model will be formulated. PUBLIC HEALTH RELEVANCE: Fragmentation of mental health system is one of the biggest challenges facing modern mental health care, according to the President's New Freedom Commission on Mental Health (2003) and the Surgeon General (U.S. Department of Health and Human Services, 1999). Understanding partnership development has potential to inform administrative and policy strategies for addressing fragmentation and unmet mental health service needs in line with the goals of Healthy People 2010.